Lighting System Combining Natural and Artificial Light

ABSTRACT

A system for lighting an interior of a building according to one example embodiment includes a curb positioned on an exterior of the building for receiving natural light. A light duct is positioned within the curb having a reflective inner surface for transferring the natural light. A light fixture is connected to an outlet of the light duct such that both natural light and artificial light are emitted from the light fixture to the building interior. A photo sensor is positioned in the building interior to sense an illumination level therein. A controller in communication with the photo sensor and the light fixture is programmed to adjust the amount of light emitted by a dimmable light source in the light fixture in response to fluctuation in the illumination level sensed in the building interior in order to maintain a desired illumination level.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority as a divisional application of U.S.patent application Ser. No. 13/238,047, entitled “Lighting SystemCombining Natural and Artificial Light” and filed on Sep. 21, 2011,which is incorporated by reference herein in its entirety.

BACKGROUND

1. Field of the Disclosure

The present invention relates generally to a lighting system and moreparticularly to a lighting system that combines both natural andartificial light.

2. Description of the Related Art

Natural light is often desired by homeowners, businesses and schools forthe many benefits it provides. Natural light offers many health benefitsin comparison with artificial light. For example, natural light mayreduce eyestrain versus artificial light. Energy savings may also berealized by optimizing the amount of natural light presented in aninterior portion of a building, a process known as “daylightharvesting.” Where more natural light is provided, less artificial lightis required thereby reducing electricity consumption during the day.

However, many buildings include rooms or areas that are lit solely byartificial lights such as incandescent lamps, fluorescent lamps or lightemitting diodes (“LEDs”). Often times, uniform illumination is notachieved in these areas. Some areas may be too bright, while others aretoo dim. It is also common for artificial lights to create otherundesired conditions such as an unintended glare or excessive ceilingbrightness. These non-uniformities are particularly troublesome in areassuch as classrooms and workplaces where reading and typing arefrequently performed for long periods of time.

Natural light is typically introduced to these areas through windowsand/or ceiling skylights. Natural light has also been introduced via oneor more light ducts that transfer natural light to an interior room of abuilding. One known system includes a motorized damper to either open orclose the duct depending on whether the natural light is desired.However, non-uniformities may persist even where natural light isprovided in a room. For example, the light level may be too high for astudent or worker seated near a window or other natural light outputwhile the light level may be too low for another student or workerseated away from the natural light output. Accordingly, it will beappreciated that a lighting system that combines natural and artificiallight to achieve a desired illumination level and distribution isdesired.

SUMMARY

A system for lighting an interior of a building according to one exampleembodiment includes a curb positioned on an exterior of the building forreceiving natural light. A plurality of light ducts is positioned withinthe curb. Each light duct has an inlet for receiving the natural lightentering the curb and a reflective inner surface for transferring thenatural light. A plurality of light fixtures for illuminating a portionof the building interior are provided. Each light fixture is connectedto an outlet of at least one of the plurality of light ducts and has alighting mount for operatively connecting a dimmable artificial lightsource thereto such that both natural light and artificial light areemitted from each light fixture to the portion of the building interior.A photo sensor is positioned in the portion of the building interiorbeing illuminated by the light fixtures for sensing an illuminationlevel in the portion of the building interior being illuminated. Acontroller in communication with the photo sensor and the light fixturesis programmed to adjust the amount of light emitted by each artificiallight source in response to fluctuation in the illumination level sensedin the portion of the building interior being illuminated resulting fromchanges in the natural light in order to maintain a desired illuminationlevel in the portion of the building interior being illuminated.

A system for lighting an interior of a building according to a secondexample embodiment includes at least one light duct having an inlet forreceiving natural light and a reflective inner surface for transferringthe natural light. Polarized glass is positioned in the path of thelight duct. A voltage source is connected to the polarized glass. Theopacity of the polarized glass changes as the voltage supplied to thepolarized glass by the voltage source changes to dim the natural lightpassed through the light duct. A light fixture is provided forilluminating a portion of the building interior. The light fixture isconnected to an outlet of the at least one light duct and has a lightingmount for operatively connecting at least one dimmable artificial lightsource thereto such that both natural light and artificial light areemitted from the light fixture to the portion of the building interior.A photo sensor is positioned in the portion of the building interiorbeing illuminated by the light fixture for sensing an illumination levelin the portion of the building interior being illuminated. A controllerin communication with the photo sensor, the light fixture and thevoltage source is programmed to adjust at least one of: (1) the amountof light emitted by the at least one artificial light source and (2) theopacity of the polarized glass in response to fluctuation in theillumination level sensed in the portion of the building interior beingilluminated in order to maintain a desired illumination level in theportion of the building interior being illuminated.

A light fixture for emitting artificial and natural light according toone example embodiment includes a lighting mount having a dimmingballast for operatively connecting at least one dimmable artificiallight source to the light fixture. An inlet is positioned at a first endof the light fixture and sized to connect to a light duct to receivenatural light from the light duct. An outlet is positioned at a bottomportion of the light fixture to emit artificial light from the at leastone dimmable light source and the natural light received from the lightduct. The light fixture includes a top portion having a sloped heightthat reduces from the first end of the light fixture to a second end ofthe light fixture opposite the first end to reflect the natural light ina manner that evenly distributes the natural light from the outlet.

A system for lighting an interior of a building according to anotherexample embodiment includes a light duct having an inlet for receivingnatural light and a reflective inner surface for transferring thenatural light. A light fixture is provided for illuminating a portion ofthe building interior. The light fixture has a reflective top surfaceand a lighting mount having a dimming ballast for operatively connectingat least one dimmable artificial light source to the light fixture. Thelight fixture is positioned to receive natural light emitted from anoutlet of the light duct on the reflective top surface thereof. Thereflective top surface is configured to reflect the natural lightreceived from the light duct to another surface to provide indirectnatural light illumination to the building interior.

A system for lighting an interior of a building according to anotherexample embodiment includes a curb positioned on an exterior of thebuilding for receiving natural light. At least one light duct ispositioned within the curb and extends into the building interior. Theat least one light duct has an inlet for receiving the natural lightentering the curb and a reflective inner surface for transferring thenatural light. A light fixture is provided for illuminating a portion ofthe building interior. The light fixture is connected to an outlet ofthe at least one light duct for receiving natural light from the lightduct. The light fixture has a lighting mount for operatively connectinga dimmable artificial light source thereto such that both natural lightand artificial light are emitted from the light fixture to the portionof the building interior. A system is included for capturing andtransferring heat collected by the curb from the natural light out ofthe curb.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of the variousembodiments, and the manner of attaining them, will become more apparentand will be better understood by reference to the accompanying drawings.

FIG. 1 is a schematic view of a lighting system that combines naturaland artificial light according to one example embodiment.

FIG. 2 is a side section view of a curb having a plurality of lightducts installed on the roof of a building for receiving and transferringnatural light according to one example embodiment.

FIG. 3 is a top plan view of a curb having light ducts arranged thereinaccording to one example embodiment.

FIG. 4 is a side elevation view of a light duct providing a section viewthrough a light fixture connected thereto according to one exampleembodiment.

FIG. 5 is a top plan view of a light fixture that emits both natural andartificial light according to one example embodiment.

FIG. 6 is a top plan view of a light fixture according to one exampleembodiment.

FIG. 7 is a side elevation view of the light fixture illustrated in FIG.6.

FIG. 8 is a first cross sectional view of the light fixture in FIG. 7taken along line 8-8.

FIG. 9 is a second cross sectional view of the light fixture in FIG. 7taken along line 9-9.

FIG. 10 is a perspective view of a light fixture according to oneexample embodiment.

FIG. 11 is a side cross sectional view of the light fixture illustratedin FIG. 10.

FIG. 12 is a schematic view of a room employing the light systemaccording to one example embodiment.

FIG. 13 is a top plan view of the curb, light ducts and light fixturesfor the configuration shown in FIG. 12 according to one exampleembodiment.

FIG. 14 is a top plan view of a control center for the lighting systemaccording to one example embodiment.

FIG. 15 is a bottom view of the control center shown in FIG. 14.

FIG. 16 is a side elevation of the control center shown in FIG. 14 withan access door partially opened.

FIG. 17 is a top plan view of a curb having a water pipe systeminstalled therein for recovering the heat captured by the curb accordingto one example embodiment.

DETAILED DESCRIPTION

The following description and drawings illustrate embodimentssufficiently to enable those skilled in the art to practice the presentinvention. It is to be understood that the disclosure is not limited tothe details of construction and the arrangement of components set forthin the following description or illustrated in the drawings. Theinvention is capable of other embodiments and of being practiced or ofbeing carried out in various ways. For example, other embodiments mayincorporate structural, chronological, electrical, process, and otherchanges. Examples merely typify possible variations. Individualcomponents and functions are optional unless explicitly required, andthe sequence of operations may vary. Portions and features of someembodiments may be included in or substituted for those of others. Thescope of the application encompasses the appended claims and allavailable equivalents. The following description is, therefore, not tobe taken in a limited sense and the scope of the present invention isdefined by the appended claims.

Also, it is to be understood that the phraseology and terminology usedherein is for the purpose of description and should not be regarded aslimiting. The use of “including,” “comprising,” or “having” andvariations thereof herein is meant to encompass the items listedthereafter and equivalents thereof as well as additional items. Unlesslimited otherwise, the terms “connected,” “coupled,” and “mounted,” andvariations thereof herein are used broadly and encompass direct andindirect connections, couplings, and mountings. In addition, the terms“connected” and “coupled” and variations thereof are not restricted tophysical or mechanical connections or couplings.

FIG. 1 shows a schematic illustration of a lighting system 10 accordingto one embodiment. Lighting system 10 includes a curb 30 positioned onan exterior portion 22 of a building 20 (FIG. 2). A portion of curb 30extends from exterior portion 22 into an interior portion 24 of building20. Dashed line 21 in FIG. 1 schematically illustrates the dividing linebetween exterior portion 22 and interior portion 24 of building 20.Building 20 may be any suitable building including, but not limited to,a residential home or apartment building, a school, or a commercialbuilding such as an office building, a warehouse or a manufacturingfacility.

With reference to FIG. 2, curb 30 is formed by a plurality of walls 32.Curb 30 includes an open portion 34 formed therein that receives naturallight from the sun. A skylight cover 36 is preferably positioned overopen portion 34 to prevent rain and debris from entering interiorportion 24 of building 20 through open portion 34. In the exampleembodiment shown in FIG. 2, curb 30 extends through the roof 26 ofbuilding 20. However, curb 30 may be positioned on any exterior portionof building 20 including an exterior wall thereof. Preferably, curb 30is positioned on a portion of building 20 that receives consistentsunlight and is clear of trees, buildings and other impediments tosunlight. It will be appreciated that curb 30 collects not only naturallight but a significant amount of heat from the natural light as well.Accordingly, in one embodiment, curb 30 is insulated in interior portion24 of building 20 in order to reduce the transfer of heat collected bycurb 30 to the interior 24 of building 20. With reference back to FIG.1, in the example embodiment illustrated, curb 30 is square shaped;however, any suitable shape may be used including a rectangular orhexagonal curb 30, a circular or oval curb 30 or an irregular shapedcurb 30. In one specific example embodiment, walls 32 form a square curb30 that is 46″ by 46″ wide and 36″ tall. Walls 32 may be constructed ofany sturdy, rigid, insulated material such as, for example aluminum orgalvanized steel.

In one embodiment, skylight cover 36 is prism shaped as shown in FIG. 2and directs the sunlight downward into curb 30. Alternatives includethose wherein skylight cover 36 is domed or flat. Skylight cover 36 issubstantially transparent or substantially translucent to permit naturallight to pass therethrough. For example, in one embodiment, skylightcover 36 is composed of ⅜″ thick prismatic borosilicate glass that is98% translucent. Additional suitable materials include, for example,acrylic, glass and polycarbonate plastic.

With reference to FIGS. 1-3, a plurality of light ducts 40 arepositioned within curb 30. Each light duct 40 includes an inlet 42positioned in curb 30 that receives natural light entering curb 30.Light ducts 40 have a reflective inner surface 44 for transferring thenatural light therethrough. In one embodiment, light ducts 40 are linedwith 98% reflective specular aluminum; however, inner surface 44 may becomposed of any suitable material having the desired level ofreflectivity. It is preferred that the inlets 42 of light ducts 40 arepositioned as close to flush with the top surface of curb 30 as possiblein order to maximize the amount of light captured by light ducts 40.However, in one embodiment, inlets 42 are recessed below the top surfaceof curb 30. In this embodiment, the inner surface of curb 30 aboveinlets 42 is reflective in order to increase the amount of lightcaptured by light ducts 40. In the example embodiment illustrated, lightducts 40 are tubular and have a circular cross section. In thisembodiment, light ducts 40 are joined by elbows 48 and connectors 49that allow the light duct 40 to change directions and reach itsdestination. In one specific example embodiment, each light duct 40 hasan 8″ diameter. Alternatively, light ducts 40 may have any suitablecross sectional shape or size such as an oval, rectangular or squarecross section; however, it will be appreciated that a circular crosssection provides optimum light transfer. In one embodiment, an interiorportion 31 of curb 30 surrounding light ducts 40 is insulated in orderto prevent cool air from interior portion 24 of building 20 from causingcondensation on light ducts 40 and/or cover 36.

With reference to FIG. 3, in the example embodiment illustrated, a totalof nine light ducts 40 are positioned in a 3×3 arrangement in curb 30.More or fewer light ducts 40 may be provided. For example, in anotherembodiment sixteen light ducts 40 are used in a 4×4 arrangement. Lightducts 40 may be arranged symmetrically or asymmetrically in curb 30 asdesired. It will be appreciated that the number of light ducts 40 andthe size of light ducts 40 and curb 30 may be selected based on theamount of natural light desired.

With reference back to FIG. 1, an output 46 of each light duct 40connects to a light fixture 50. Each light fixture 50 is positioned asdesired to illuminate a portion of interior 24 of building 20. Thenatural light from light duct 40 exits output 46 and is emitted intointerior 24 from light fixture 50. Each light fixture 50 may beconnected to one or more than one output 46 of a light pipe 40 dependingon the amount of natural light desired for a given light fixture 50. Inone embodiment, light fixture 50 is a 2′ by 4′ lay-in fixture or a 2′ by2′ round or square fixture.

With reference to FIG. 4, light fixture 50 also includes at least onedimmable artificial light source 60 such as, for example one or moreincandescent and/or fluorescent lamps or one or more LEDs operativelyconnected thereto. In this manner, both natural and artificial light areemitted from each light fixture 50. Artificial light source 60 may bedimmed by altering amount of light emitted by each lamp using a dimmingballast 61 or, where more than one lamp is used, by changing the numberof lamps that are illuminated. It will be appreciated that altering theamount of light emitted by each lamp allows for dimming along asubstantially continuous illumination range while changing the number oflamps that are illuminated only permits dimming in fixed increments.Accordingly, the former is preferred. One example light source suitablefor use with lighting system 10 is an RT5™ fluorescent fixture sold byLithonia Lighting®, which is an Acuity Brands® company.

A top view of an example light fixture 50 is illustrated in FIG. 5. Inthe example embodiment illustrated, two artificial light sources 60 a,60 b in the form of dimmable fluorescent lamps run longitudinally alonglight fixture 50. Output 46 of light duct 40 transmits natural light tolight fixture 50 that is emitted from the output 62 of light fixture 50.As a result, both artificial light and natural light are emitted fromlight fixture 50, artificial light from artificial light sources 60 a,60 b and natural light received from light duct 40. It will beappreciated that light fixture 50 may provide direct or indirect lightas desired depending the orientation and placement of the light fixture50. A cover 54 composed of a diffuser formed from prismatic acrylic,glass, frosted glass, etc. may optionally be positioned across theoutput face 62 of light fixture 50 to distribute the light emitted fromlight fixture 50 and hide the internal light source arrangement. Thispreserves the aesthetic appearance of light fixture 50 so that lightfixture 50 appears as a conventional light fixture.

With reference to FIGS. 6-9, a light fixture 150 is shown according toone example embodiment. Light fixture 150 includes a top portion 151, abottom portion 152, a first end 153, a second end 154 and two sideportions 155, 156. End 153 includes an inlet 158 therein that is sizedand shaped to receive outlet 46 of light duct 40. Natural lighttransferred through light duct 40 exits outlet 46 and enters lightfixture 150 through inlet 158. In the example embodiment illustrated,inlet 158 has a circular cross section in order to receive the examplelight duct 40 illustrated in FIGS. 1-3. An outlet 160 of light fixture150 is formed in bottom portion 152 as a rectangular opening. Outlet 160extends substantially across the entire length L and width W of bottomportion 152.

Top portion 151 of light fixture includes a sloped height that reducesfrom a first height H1 at end 153 having inlet 158 to a second height H2at end 154 opposite thereto. The inner surface 162 of top portion isreflective in order to reflect the natural light from inlet 158 downwardout of outlet 160. It will be appreciated that the use of a sloped topportion 151 provides a substantially even distribution of the naturallight from outlet 160 along the length L of bottom portion 152. In theexample embodiment illustrated, top portion 151 includes a multi-facetedsurface having a planar center facet 151 a that slopes from height H1near end 153 to height H2 near end 154. The width W1 of center facet 151a increases symmetrically along length L from end 153 to end 154. Planarside facets 151 b, 151 c are positioned on opposite sides of centerfacet 151 a. As shown in FIG. 8, side facets 151 b, 151 c are angledwith respect to bottom portion 152. Each side facet 151 b, 151 c has awidth W2 that decreases symmetrically along length L from end 153 to end154 as shown in FIGS. 6, 8 and 9. Facets 151 a, 151 b, 151 c permit asubstantially even distribution of the natural light from outlet 160along the width W of bottom portion 152. In one alternative embodiment,top portion 151 includes a curved, concave top inner surface 162 insteadof the multi-faceted configuration shown to create a substantially evendistribution of the natural light from outlet 160 along the width W ofbottom portion 152.

Light fixture 150 includes at least one artificial light source, such asfluorescent lamp(s) or LED(s), operatively connected to a correspondingdimming ballast or LED driver therein. In the example embodimentillustrated, a pair of dimmable fluorescent lamps 164 a, 164 b extendslongitudinally along length L of light fixture 150. As a result, in thisconfiguration, both natural light and artificial light are emitted in arelatively even distribution from outlet 160 of light fixture 150. Eachlamp 164 a, 164 b is mounted in a lighting mount 168 and operativelyconnected to a corresponding dimming ballast 170. In one exampleembodiment, between 0 and 10 volts are provided to the ballasts 170. Asdiscussed above, a cover 166 composed of a diffuser formed fromprismatic acrylic, glass, frosted glass, etc. may optionally bepositioned across the face of output 160 of light fixture 150 todistribute the light emitted from output 160 and to preserve theaesthetic appearance of light fixture 150.

With reference to FIGS. 10 and 11, a light fixture 169 that providesindirect natural light and direct artificial light is shown according toone example embodiment. Light fixture 169 is suspended from a ceiling178 by a cable or hanging stem 177. As shown in FIG. 11, light duct 40feeds natural light from its outlet 46 to inlet 158 of light fixture 150discussed above in conjunction with FIGS. 6-9 except that in the exampleembodiment shown in FIGS. 10 and 11, light fixture 150 may be providedwithout light source(s) 164 therein. Rather, light fixture 150 is usedto provide an even distribution of natural light from outlet 160. Outlet160 is positioned above a louvered opening 171 in ceiling 178. Lightfixture 169 is in turn positioned below louvered opening 171 such thatlouvered opening 171 extends longitudinally along light fixture 169. Inone embodiment, louvered opening 171 is 46″ long and 12″ wide. Naturallight from light duct 40 is emitted from louvered opening 171 onto areflective top surface 175 of light fixture 169. In one embodiment, topsurface 175 includes a specular hammer tone natural light finish. Thenatural light is reflected from reflective top surface 175 onto ceiling178 and from ceiling 178 to the room or area where light fixture 169 isinstalled. Reflective top surface 175 is angled with respect to ceiling178 to reflect the natural light received from light duct 40 away from acenterline C of light fixture 169 toward ceiling 178 to maximize theamount of light reflected from ceiling 178 into the room or area inwhich light fixture 169 is installed instead of back onto top surface175. In this manner, light fixture 169 is able to provide indirectnatural light to interior 24 of building 20. A flash shield 174, such asa specular aluminum flash shield or a luminous acrylic diffuser, isshown extending from each longitudinal edge 175 a, 175 b of top surface175 and forming an obtuse angle with top surface 175. Flash shield 174acts as a visor to shield observers from the relatively bright, focusedreflection on top surface 175. It will be appreciated that the amount ofnatural light emitted depends, in part, on the size of opening 171 andthe size of light duct 40. In one embodiment, ceiling 178 is 70%reflective in order to promote the reflection of natural light off ofits surface. It will be appreciated that although light fixture 169 isshown mounted on ceiling 178, light fixture may be mounted on anysuitable surface including a vertical wall.

Light fixture 169 includes at least one artificial light source, such asfluorescent lamp(s) or LED(s), operatively connected to a correspondingdimming ballast or LED driver therein. In the example embodimentillustrated, a pair of dimmable fluorescent lamps 164 a, 164 b extendslongitudinally along the length of light fixture 169. In thisconfiguration, artificial light is emitted from light fixture 169directly to the room or area in which light fixture 169 is installed.Each lamp 164 a, 164 b is mounted in a lighting mount 168 andoperatively connected to a corresponding dimming ballast 170. A covermay be positioned across the face of light fixture 169 over fluorescentlamps 164 a, 164 b as desired. In the example embodiment illustrated, ashielding louver 176, such as an acrylic shielding louver, extendslongitudinally along a center portion of light fixture 169 and adiffuser 172, such as an acrylic diffuser, extends longitudinally alonglight fixture 169 adjacent to fluorescent lamps 164 a, 164 b on eachside of shielding louver 176. In this configuration, shielding louver176 and diffusers 172 combine to form a cover over lamps 164 a, 164 b.An artificial light reflector 173 is also shown extending longitudinallyalong light fixture 169 on each side of the cover. Light reflector 173aids in directing the artificial light emitted by lamps 164 a, 164 btoward the room or area in which light fixture 169 is installed.

FIGS. 12 and 13 schematically illustrate an example configuration oflighting system 10 in a room 70 such as a classroom or an office. Theposition of curb 30 on the roof of building 20 above room 70 isillustrated in dashed lines in FIG. 12. In this example, nine lightducts 40 are positioned in curb 30, each connected to a correspondinglight fixture 50 such as light fixture 150. The nine light fixtures 50are spaced symmetrically along the ceiling of room 70 to provide bothnatural and artificial light to room 70. At least one photo sensor 80 ispositioned in room 70 that senses the illumination level in room 70.Photo sensor 80 is in communication with a programmable controller 82.This communication may be established via a wired or wireless connectionas is known in the art. Controller 82 may include a single controller ormultiple control units in communication with each other. Each controllermay include one or more processors that include (or are communicativelycoupled to) memory having computer executable storage instructionswhich, when executed by the processor(s), cause the controller(s) toperform their programmed function. Controller 82 is also incommunication with the ballast(s) or driver(s) of light fixtures 50.

Controller 82 is programmed to control the dimming of artificial lightsources 60 in light fixtures 50 in response to fluctuation in the amountof total light sensed by photo sensor(s) 80 in order to maintain adesired illumination level in room 70. For example, natural light issupplied through light ducts 40 during the day but not during the night.Therefore, if a constant amount of artificial light were supplied fromlight fixtures 50, room 70 would receive more total light during the daythan during the night. This would cause room 70 to be too dark at nightand/or too bright during the day. Accordingly, when photo sensor 80senses that the illumination level in room 70 is too high, controller 82dims the artificial light sources 60 of light fixtures 50 in order toreach the desired illumination level. Conversely, when photo sensor 80senses that the illumination level in room 70 is too low, controller 82turns the artificial light sources 60 of light fixtures 50 up in orderto brighten the room to reach the desired illumination level. It will beappreciated that the amount of natural light transmitted from curb 30through light ducts 40 will fluctuate throughout the day based on suchfactors as the position of the sun as it goes from rising in the morningto setting in the evening, the time of year, and whether the sky isclear, cloudy, foggy, or hazy. In order to account for this fluctuation,controller 82 is programmed to continually monitor the illuminationlevel sensed by photo sensor 80 and to continually adjust the brightnessof artificial light sources 60.

Controller 82 may be programmed to adjust artificial light sources 60collectively as a group. For example, if the example configuration shownin FIGS. 12 and 13 is used, controller 82 may be used to adjust theartificial light sources 60 of all nine light fixtures 50 jointly.Alternatively, controller 82 may be programmed to adjust the artificiallight sources 60 of light fixtures 50 individually or in smaller groups.For example, if the configuration shown in FIGS. 12 and 13 is used,controller 82 may be programmed to adjust the artificial light sources60 of each of the nine light fixtures 50 individually or in groups, suchas adjusting the light fixtures 50 in sets of three. This isparticularly useful where natural light is also provided to the room 70via one or more windows because it allows the artificial lights 60 nearthe windows to be dimmed to a greater degree than the artificial lights60 farther away from the windows. In this manner, lighting system 10combines artificial light and natural light to provide a substantiallyuniform illumination level and distribution that dynamically adjusts tochanges in the amount of natural light available. While FIGS. 12 and 13show all of the light fixtures 50 installed within a single room 70, itwill be appreciated that a single curb 30 may feed natural light tolight fixtures 50 in multiple rooms. As discussed above, controller 82may adjust these light fixtures 50 collectively, individually or ingroups, such as on a room by room basis.

A user input device 84 is provided that is in communication withcontroller 82. User interface 84 may be provided physically withcontroller 82 or it may be spaced therefrom. User input device 84 isconfigured to receive an input from a user of the desired illuminationlevel for all or one or more portions of the areas controlled bycontroller 82. For example, a uniform desired illumination level may beset for an entire building or it may be desired that some rooms or areasare brighter than others. The user input device 84 may include an “on”setting and an “off” setting similar to a conventional light switch.When the “on” setting is selected, controller 82 will maintain thedesired illumination level. When the “off” setting is selected,controller 82 will turn off artificial light sources 60 leaving only thenatural light from light ducts 40. Further, user input device 84 mayinclude a programmable timer setting that allows the user to setlighting system 10 to default to the “on” setting during predeterminedtimes of the day when the room or area is frequently occupied and todefault to the “off” setting when it is anticipated that the room orarea will be empty.

User input device 84 may include any conventional input means including,but not limited to, one or more buttons, dials, or levers, a mechanicalor touch screen keypad, or a mouse for inputting user settings. Userinput device 84 may also include a display portion such as a graphicaluser interface or one or more LED indicator lights that displayinformation such as the system settings to the user. User input device84 may be employed on a building-wide basis to control the lighting foran entire building. For example, user input device 84 may be placed nearthe thermostat in a home or in a utility room in a commercial facilityto control the building's lighting. Alternatively, user input device 84may be used to provide local control of individual rooms or portions ofa building by placing a user input device 84 on the wall like a lightswitch.

In one embodiment, an occupancy sensor 81 is provided in one or morerooms or areas. Occupancy sensor 81 is in communication with controller82. Occupancy sensor 81 allows controller 82 to provide one illuminationsetting when the room or area is occupied another when it is vacant. Theoccupancy settings may be provided by the user at user input device 84.

With reference back to FIGS. 2 and 3, in one embodiment, conventionalpolarized glass 90 is positioned in the path of one or more of lightducts 40. Polarized glass 90 is connected to a voltage source 92. Whenno voltage is applied, polarized glass 90 is clear to permit the passageof light therethrough. As voltage is applied, polarized glass 90 froststo block a portion of the light from passing through. By varying theapplied voltage, it's possible to vary the opacity of polarized glass 90from clear to dark or any shade in between. In one example embodiment,between 0 and 10 volts are provided from voltage source 92 to polarizedglass 90. Voltage source 92 is in communication with controller 82.Controller 82 is programmed to adjust the voltage supplied to polarizedglass 90 in order to achieve the desired illumination level set by theuser. As a result, in this embodiment, as the amount of natural lightentering room 70 through light ducts 40 fluctuates, controller 82 may beprogrammed to maintain the desired illumination level by dimming theartificial light sources, by increasing the opacity of polarized glass90 to dim the natural light or both.

In the example embodiment illustrated, polarized glass 90 is positionedwithin curb 30 at the inlet 42 of light ducts 40; however, polarizedglass 90 may be positioned at any other suitable point including atoutlet 46 of light ducts 40 or at an intermediate point. One sheet ofpolarized glass 90 may be positioned over the inlets 42 of all of thelight ducts 40 in a given curb 30. In this configuration, the naturallight to each light fixture 50 can be uniformly dimmed or brightened byadjusting the voltage supplied to the sheet. Alternatively, multiplesheets of polarized glass 90 may be used in order to permitdimming/brightening of the natural light per each individual lightfixture 50 or in groups of light fixtures 50. For example, in FIG. 3,two sheets of polarized glass 90 a, 90 b are provided. Sheet 90 a coverssix of the nine light ducts 40 and therefore permits dimming of thenatural light to a corresponding six light fixtures 50. Sheet 90 bcovers the remaining three light ducts 40 and permits dimming of thenatural light to three light fixtures 50.

In some instances, it may be desired to darken a room receiving combinednatural and artificial during the daytime. For example, a teacher maywish to darken a classroom in order to show a film or a day care centermay wish to darken a nursery for naptime. Accordingly, in oneembodiment, user input device 84 includes a setting for darkening all ora portion of the light fixtures 50 in a room. When this setting isselected, controller 82 turns off the artificial light sources 60 inlight fixtures 50 and increases the opacity of polarized glass 90 toblock natural light from passing through light ducts 40 into lightfixtures 50.

With reference to FIGS. 14-16, a lighting control center 100 accordingto one example embodiment is shown. In this embodiment, the controlcomponents for lighting system 10 including photo sensor 80, occupancysensor 81, controller 82 and voltage source 92 are prewired throughcontrol center 100 to provide a central access point for the respectivecontrol connections. In one embodiment, control center 100 includes aconventional electrical box 102 formed in the ceiling of the room orarea being illuminated such as room 70 shown in FIG. 12. In one specificexample embodiment, electrical box 102 is formed from a 22-gauge steelenclosure 104 having a hinged steel door 106 attached thereto. Wherecontrol center 100 is installed in the room or area being illuminated,an exterior face 106 a of hinged door 106 may be tiled or otherwisecovered to match the aesthetic appearance of the ceiling upon which itis installed. Photo sensor 80 and occupancy sensor 81 are each mountedon door 106 and wired to a transformer relay 108 positioned inelectrical box 102. Control center 100 may also include an emergencybypass relay 110 for activating emergency lighting in the event of apower outage. Utility and emergency power are received in a junction box112 that is insulated from the lower voltage components in electricalbox 102 by barrier 114. A set of signal connections 116 is provided tomake the desired connections between controller 82, voltage supply 92,the dimming ballasts, photo sensor 80 and occupancy sensor 81. Power issupplied to these components as needed through a corresponding bridge orpower supply 118.

With reference to FIG. 17, as discussed above, curb 30 collects asignificant amount of heat from the natural light it receives. In theexample embodiment illustrated, a water pipe system 120 runs through theinterior of curb 30 outside of and above light ducts 40. The heatcollected by curb 30 is transferred to water in water pipe system 120.As shown in FIG. 17, care must be taken to ensure that water pipe system120 does not block the light entering curb 30 from reaching light ducts40. As a result, in the example embodiment illustrated, water pipesystem 120 is arranged in a grid formation around light ducts 40. In onespecific embodiment, water pipe system 120 is comprised of 1″ diameterblack copper piping. Water pipe system 120 includes at least one inlet122 a that provides water to system 120 and at least one outlet 122 bthat permits removal of water from system 120 so that the heat collectedby curb 30 may be captured thereby creating additional energy savings. Acorresponding valve 124 is positioned at inlet 122 a and/or outlet 122 bto control the flow of water through water pipe system 120. Valve 124opens to permit the domestic cold water of building 20 to fill waterpipe system 120. Valve 124 may be thermostatically operated such thatwhen the water reaches a predetermined temperature, valve 124automatically opens to allow the water inside curb 30 to flow out ofoutlet 122 b and to fill the pipes in curb 30 with new water to beheated. The heated water may then be fed into the building's waterheater thereby reducing the amount by which the water in the waterheater needs to be heated in order to supply hot water to building 20.The heated water may also be fed into the HVAC system of building 20 tobe used as a heat source. In order to further enhance the energysavings, a photovoltaic cell may be provided on the exterior 22 ofbuilding 20, such as on the roof 26 adjacent to curb 30. Thephotovoltaic cell may then be used to power automated valves 124. If thedomestic cold water does not provide sufficient pressure to move thewater through water pipe system 120, a pump, which may also be poweredby the photovoltaic cell, may be used to assist.

With reference back to FIG. 1, in an alternative embodiment, an air duct130 is connected to curb 30 that permits removal of hot air from insidecurb 30. Air duct 130 may pass through or into curb 30 or it may simplybe connected at a wall 32 of curb 30. Air duct 130 may be used with orwithout water pipe system 120. During the winter months, the hot airtaken from curb 30 may be transferred to a portion of the interior 22 ofbuilding 20 to provide additional heat therein. During the summermonths, the hot air taken from curb 30 may simply be vented to anexterior portion of building 20 in order prevent excessive heataccumulation in building 20. The photovoltaic cell discussed above mayalso be provided in this embodiment to power a fan in fluidcommunication with air duct 130 that may be used to force the hot airfrom within curb 30 to its destination.

It will be appreciated that lighting system 10 may be used to achieve asubstantially uniform illumination. Lighting system 10 provides bothartificial and natural light and, as a result, offers health benefitsand energy savings in comparison with lighting systems that utilize onlyartificial light. Further, by capturing the heat from curb 30 usingwater or forced air, solar energy is harnessed as a natural resourcethat can be used by building 30 to offset energy costs and create a“greener” facility.

The foregoing description of several embodiments has been presented forpurposes of illustration. It is not intended to be exhaustive or tolimit the application to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. It is understood that the invention may be practiced in waysother than as specifically set forth herein without departing from thescope of the invention. It is intended that the scope of the applicationbe defined by the claims appended hereto.

What is claimed is:
 1. A system for lighting an interior of a building,comprising: a curb positioned on an exterior of the building forreceiving natural light; a plurality of light ducts positioned withinthe curb and extending into the building interior, each light ducthaving an inlet for receiving the natural light entering the curb and areflective inner surface for transferring the natural light; a pluralityof light fixtures for illuminating a portion of the building interior,each light fixture connected to an outlet of at least one of theplurality of light ducts and having a lighting mount for operativelyconnecting a dimmable artificial light source thereto such that bothnatural light and artificial light are emitted from each light fixtureto the portion of the building interior; a photo sensor positioned inthe portion of the building interior being illuminated by the lightfixtures for sensing an illumination level in the portion of thebuilding interior being illuminated; and a controller in communicationwith the photo sensor and the light fixtures programmed to adjust theamount of light emitted by each artificial light source in response tofluctuation in the illumination level sensed in the portion of thebuilding interior being illuminated resulting from changes in thenatural light in order to maintain a desired illumination level in theportion of the building interior being illuminated.
 2. The system ofclaim 1, further comprising a cover positioned on the curb, at least aportion of the cover being one of substantially transparent andsubstantially translucent to allow natural light to pass therethrough.3. The system of claim 2, wherein the cover is prism shaped.
 4. Thesystem of claim 1, wherein the outlet of each light duct is positionedrelative to its respective light fixture to distribute the natural lightsubstantially evenly from the light fixture.
 5. The system of claim 4,wherein at least one of the light fixtures has an inlet that ispositioned at a first end of the light fixture and connected to theoutlet of at least one of the plurality of light ducts, and the at leastone light fixture includes an outlet at a bottom portion of said lightfixture and a top portion having a sloped height that reduces from thefirst end of said light fixture to a second end of said light fixtureopposite the first end to evenly distribute the natural light from theoutlet of said light fixture.
 6. The system of claim 1, wherein the curbis insulated to reduce the transfer of heat collected by the curb fromthe natural light through the interior of the building.
 7. The system ofclaim 6, wherein an interior portion of the curb surrounding the lightducts is insulated to prevent condensation on the light ducts.
 8. Thesystem of claim 1, further comprising a user input device incommunication with the controller for receiving an input from a user ofthe desired illumination level.
 9. The system of claim 1, furthercomprising polarized glass positioned in the path of at least one of thelight ducts connected to a voltage source, wherein the opacity of thepolarized glass changes as the voltage supplied to the polarized glassby the voltage source changes to dim the natural light passed throughsaid light duct.
 10. The system of claim 9, wherein the controller is incommunication with the voltage source and programmed to adjust thevoltage supplied to the polarized glass to achieve the desiredillumination level.
 11. A system for lighting an interior of a building,comprising: at least one light duct having an inlet for receivingnatural light and a reflective inner surface for transferring thenatural light; polarized glass positioned in the path of the light duct;a voltage source connected to the polarized glass, wherein the opacityof the polarized glass changes as the voltage supplied to the polarizedglass by the voltage source changes to dim the natural light passedthrough the light duct; a light fixture for illuminating a portion ofthe building interior, the light fixture connected to an outlet of theat least one light duct and having a lighting mount for operativelyconnecting at least one dimmable artificial light source thereto suchthat both natural light and artificial light are emitted from the lightfixture to the portion of the building interior; a photo sensorpositioned in the portion of the building interior being illuminated bythe light fixture for sensing an illumination level in the portion ofthe building interior being illuminated; and a controller incommunication with the photo sensor, the light fixture and the voltagesource and being programmed to adjust at least one of: (1) the amount oflight emitted by the at least one artificial light source and (2) theopacity of the polarized glass in response to fluctuation in theillumination level sensed in the portion of the building interior beingilluminated in order to maintain a desired illumination level in theportion of the building interior being illuminated.
 12. The system ofclaim 11, wherein the polarized glass is positioned at the inlet of thelight duct.
 13. The system of claim 11, further comprising a user inputdevice in communication with the controller for receiving an input froma user of the desired illumination level.
 14. The system of claim 13,wherein the user input includes a setting for darkening the portion ofthe building interior being illuminated and in response to a selectionof the darkening setting, the controller is programmed to turn off theartificial light source and increase the opacity of the polarized glassto reduce the amount of natural light emitted from the light fixture.